Systems for Highly Efficient Solar Power Conversion

ABSTRACT

A high efficiency photovoltaic DC-DC converter achieves solar power conversion from high voltage, highly varying photovoltaic power sources to harvest maximum power from a solar source or strings of panels for DC or AC use, perhaps for transfer to a power grid at high power levels with coordinated control possible for various elements. Photovoltaic DC-DC converters can achieve efficiencies in conversion that are extraordinarily high compared to traditional through substantially power isomorphic photovoltaic DC-DC power conversion capability that can achieve 97%, 98%, 99.2% efficiency, or even only wire transmission losses. Switchmode impedance or voltage conversion circuit embodiments may have pairs of photovoltaic power interrupt switch elements and pairs of photovoltaic power shunt switch elements to first increase voltage and then decrease voltage as part of the desired photovoltaic DC-DC power conversion.

This application is a continuation-in-part of prior InternationalApplication No. PCT/US2008/080794, filed Oct. 22, 2008, which claimsbenefit of and priority to U.S. Provisional Application No. 60/982,053,filed Oct. 23, 2007, and U.S. Provisional Application No. 60/986,979,filed Nov. 9, 2007; this application is a continuation-in-part of priorInternational Application No. PCT/US2008/070506, filed Jul. 18, 2008,which is a continuation-in-part of prior International Application No.PCT/US2008/060345, filed Apr. 15, 2008, and which is acontinuation-in-part of prior International Application No.PCT/US2008/057105, filed Mar. 14, 2008, and which claims benefit of andpriority to U.S. Provisional Application No. 60/980,157, filed Oct. 15,2007, U.S. Provisional Application No. 60/982,053, filed Oct. 23, 2007,and U.S. Provisional Application No. 60/986,979, filed Nov. 9, 2007;this application is a continuation-in-part of prior InternationalApplication No. PCT/US2008/060345, filed Apr. 15, 2008, which is acontinuation-in-part of prior International Application No.PCT/US2008/057105, filed Mar. 14, 2008, and which claims benefit of andpriority to U.S. Provisional Application No. 60/980,157, filed Oct. 15,2007, U.S. Provisional Application No. 60/982,053, filed Oct. 23, 2007,and U.S. Provisional Application No. 60/986,979, filed Nov. 9, 2007;this application is a continuation-in-part of prior InternationalApplication No. PCT/US2008/057105, filed Mar. 14, 2008, which claims thebenefit of and priority to U.S. Provisional Application No. 60/980,157,filed Oct. 15, 2007, U.S. Provisional Application No. 60/982,053, filedOct. 23, 2007, and U.S. Provisional Application No. 60/986,979, filedNov. 9, 2007; each hereby incorporated herein by reference.

TECHNICAL FIELD

This invention relates to the technical field of solar power,specifically, methods and apparatus for converting electrical power fromsome type of solar energy source to make it available for use in avariety of applications. The invention focuses on systems that use DC-DCconversion to harvest maximum power from a solar cell, a solar panel, orstrings of panels so that this power can be provided for DC or AC use,perhaps for transfer to a power grid or the like. Unusually efficientcircuitry and control methods are provided so that minimal power is lostin the process of achieving the DC-DC conversion to achieve efficienciesin conversion that are extraordinarily high compared to traditionalsystems.

BACKGROUND

Solar power is one of the more desirable types of renewal energy. Foryears it has been touted as one of the most promising for ourincreasingly industrialized society. Even though the amount of solarpower theoretically available far exceeds most, if not all, other energysources (renewable or not), there remain practical challenges toutilizing this energy. In general, solar power remains subject to anumber of limitations that have kept it from fulfilling the promise itholds. In one regard, it has been a challenge to implement in a mannerthat provides adequate electrical output as compared to its cost. Thepresent invention addresses an important aspect of this in a manner thatsignificantly increases the ability to cost-effectively permit solarpower to be electrically harnessed so that it may be a cost-effectivesource of electrical power.

One of the most efficient ways to convert solar power into electricalenergy is through the use of solar cells. These devices create aphotovoltaic DC current through the photovoltaic effect. Often thesesolar cells are linked together electrically to make a combination ofcells into a solar panel or a PV (photovoltaic) panel. Voltage, current,and power levels may be provided at an individual domestic level, suchas for an individual house or the like. Similarly, large arrays of many,many panels may be combined in a sea of panels to create significant,perhaps megawatt outputs to public benefit perhaps as an alternative tocreating a new coal burning power plant, a new nuclear power plant, orthe like. PV panels are often connected in series to provide highvoltage at a reasonable current. This may be accomplished to makeelectrical interconnect losses low. The output of a solar cell or asolar panel, or even combinations thereof, is frequently then convertedto make the electrical power most usable since the power convertersoften employed can use high voltage input more effectively. Electricalrequirements of producing power from a solar panel can make it difficultto achieve this conversion in as efficient a manner as desired.Conventional power converters sometimes have their input handled by anMPPT (maximum power point tracking) circuit to extract the maximumamount of power from one or more or even a string of series connectedpanels. This constraint can make the conversion process less efficient.And because of the nature of solar panels and insolation, suchconversion usually needs to have the ability to both increase anddecrease a parameter (impedance, voltage, or the like).

Another problem that arises with this approach is that often the PVpanels act as current sources and when combined in a series string, thelowest power panel can limit the current through every other panel.Furthermore, solar cells historically have been made from semiconductorssuch as silicon pn junctions. These junctions or diodes convert sunlightinto electrical power. These diodes can have a characteristically lowvoltage output, often on the order of 0.6 volts. Such cells may behavelike current sources in parallel with a forward diode. The outputcurrent from such a cell may be a function of many construction factorsand, is often directly proportional to the amount of sunlight.

Focusing first on the MPPT aspect, it can be understood that the lowvoltage of such a solar cell can be difficult to convert to powersuitable for supplying power to an electric power grid. Often, manydiodes are connected in series on a photovoltaic panel. For example, apossible configuration could have 36 diodes or panels connected inseries to make 21.6 volts. With the shunt diode and interconnect lossesin practice such panels might only generate 15 volts at their maximumpower point (MPP). For some larger systems having many such panels, even15 volts may be too low to deliver over a wire without substantiallosses. In addition, typical systems today may combine many panels inseries to provide voltages in the 100's of volts in order to minimizethe conduction loss between the PV panels and a power converter.

Electrically, however, there can be challenges to finding the rightinput impedance for a converter to extract the maximum power from such astring of PV panels. The aspect of extracting power at a maximum powerpoint is often referred to as MPP tracking. Some such systems exist,however, there remain limitations, some of which are discussed here.This constraint can even make the conversion process less efficient.First, the PV panels may act as current sources. As such, the panelproducing the lowest current may limit the current through the wholestring. In an undesirable case, if one weak panel is producingmoderately less, it might become back biased by the remainder of thepanels. Reverse diodes can be placed across each panel to limit thepower loss in this case and to protect the panel from reverse breakdown.

In systems, at least the following problems can arise and cause somedegree of loss in solar energy harvesting:

-   -   A. Non-uniformity between panels.    -   B. Partial shade    -   C. Dirt or accumulated matter blocking sunlight    -   D. Damage to a panel    -   E. Non-uniform degradation of panels over time

It may also be troublesome when expensive PV panels are placed in seriesand the weakest panel limits the power from every other panel.Unfortunately, the series connection may be desired to get high enoughvoltage to efficiently transmit power through a local distribution to aload, perhaps such as a grid-tied inverter. Further, in many systems,the PV panels may be located on a rooftop, such as for a residentialinstallation. And the inverter is often located at a distance from therooftop, such as by the power meter or the like. So in embodiments, away to connect the panels in series but not suffer the losses caused bythe lowest power panel, or any series parallel combination, may beneeded. There may also be a desire to use unlike types of panels at thesame time perhaps without regarding to the connection configurationdesired (series or parallel, etc.) as well as other brands of componentssuch as traditional inverters and the like that achieve traditionalinverting.

Whether for maximum power point tracking or conversion efficiency, thetechniques of photovoltaic power conversion have been recognized as animportant limit to solar energy ultimately realizing its potential.Methods of solar power conversion have been proposed that utilize DC/DCconverters on each panel along with an MPP circuit as one attempt toenhance the efficiency of energy harvesting when utilizing strings ofsolar panels. Such attempts, however, have resulted in unacceptably lowefficiencies that have made such approaches impractical. Thesetechniques have even been dismissed to some degree by those consideringsuch issues. For example, in the article by G. R. Walker, J. Xue and P.Semia entitled “PV String Per-Module Maximum Power Point EnablingConverters” those authors may have even suggested that efficiency losseswere inevitable but that this module approach held advantages, eventhough it was attended by poor efficiency. There seems to have been anacceptance that MPPT aspects inevitably led to low efficiencyconversion. Similarly, two of the same authors, G. R. Walker and P.Semia in the article entitled “Cascaded DC-DC Converter Connection ofPhotovoltaic Modules” suggested that the needed technologies are alwaysat an efficiency disadvantage. These references even include anefficiency vs. power graph showing a full power efficiency ofapproximately 91%. Operation of expensive PV panels with operationthrough a low efficiency converter is simply not acceptable in themarketplace. The present invention shows that such inefficiencies arenot inevitable and highly efficient operation can in fact be achieved insuch operations.

Another less understood problem with large series strings of PV panelsmay be with highly varying output voltage, the inverter stage drivingthe grid my need to operate over a very wide range also lowering itsefficiency. Again, this constraint can also limit conversion efficiency.It may also be a problem if during periods of time when the invertersection is not powering the grid that the input voltage to this stagemay increase above regulatory limits. Or conversely, if the voltageduring this time is not over a regulatory limit then the finaloperational voltage may be much lower than the ideal point of efficiencyfor the inverter.

In addition, there may be start-up and protection issues which addsignificant cost to the overall power conversion process. Other lessobvious issues affecting Balance of System (BOS) costs for a solar powerinstallation are also involved. Thus, what at least one aspect ofelectrical solar power needs is an improvement in efficiency in theconversion stage of the electrical system. The present inventionprovides this needed improvement.

DISCLOSURE OF THE INVENTION

As mentioned with respect to the field of invention, the inventionincludes circuitry aspects which may be combined in different ways. Thefollowing descriptions are provided to list elements and describe someof the embodiments of the present invention. These elements are listedwith initial embodiments, however it should be understood that they maybe combined in any manner and in any number to create additionalembodiments. The variously described circuitry and system examples andpreferred embodiments should not be construed to limit the presentinvention to only the explicitly described circuit, systems, techniques,and applications. Further, this description should be understood tosupport and encompass descriptions and claims of all the variousembodiments, circuits, systems, techniques, methods, devices, andapplications with any number of the disclosed elements, with eachelement alone, and also with any and all various permutations andcombinations of all elements in this or any subsequent application.

In various embodiments, the present invention discloses systems,circuits, and different initial exemplary architectures through whichone may achieve some of the goals of the present invention. Systemsprovide alternating modes of photovoltaic conversion, high efficiencyconversion designs, and even multimodal conversion techniques. Somearchitectures may combine a PV panel with MPP and even a dual mode,highly efficient power conversion circuitry to make what may be referredto as a Power Conditioner (PC) element. As discussed below, such PowerConditioners may be combined in series or parallel or any combination ofseries/parallel and can be designed so that the solar panels willlargely or even always produce their full output while also providinghigh efficiency DC-DC conversion. Even differing types of panels havingdifferent output characteristics may be combined to produce maximumpower from each panel. In some designs, a series string may be used toget a high voltage useful for power transmission, and each PowerConditioner can be designed to make its maximum power whilesimultaneously providing highly efficient DC-DC conversion. Each of theDC photovoltaic outputs can at times present a relatively high voltageand high power; further, because of the nature of solar insolation,these voltages and powers usually are highly varying—at times there isno insolation (at night) and at times it is very intense (e.g., mid dayon a sunny day).

As to the MPPT aspect, in embodiments, this invention may permit eachand every panel to individually produce its maximum power therebyharvesting more total energy from the overall system. Systems may beconfigured with an MPP circuit and a highly efficient power conversioncircuit on each panel. These circuits may be made as simple inexpensivecircuitry to perhaps perform several functions. First, MPPT can beachieved and this circuit may be designed to extract the maximum poweravailable from each and every panel. Second, it may be configured totransform to an impedance or voltage which naturally combines with theother panels in a series string. This circuit may also be configured forparallel connected panels or even for single cells or strings within apanel. Embodiments may be configured so that the output may be a highervoltage output (for example, 400V). Additionally, configurations mayallow for an easy to administer overvoltage or other protection, perhapseven with or without feedback elements that control the system to avoidan overvoltage or other condition.

The addition of individual MPP circuitry to act upon a panel may even beconfigured so as to provide an inexpensive addition and, in someembodiments, may replace the need for the same function in the powerconverter. The circuitry may be added to the PV panels and may not needto be repeated in a grid-tied inverter. This may thus result in the sametotal circuitry with significant advantage. In embodiments there mayactually be several small MPP converters replacing one large one.Importantly from some perspectives, this can be achieved throughconversion circuitry and control that can provide highly efficient DC-DCconversion even with 97%, 98%, 99.2%, or essentially even wiretransmission loss efficiencies which can be considered the highestpossible while also achieving MPPT operation for the panels. This mayresult in even greater energy harvesting and better cost result.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic of a conversion system according to oneembodiment of the invention for a single representative solar source.

FIG. 2 shows a schematic of a sea of interconnected strings of panelsaccording to one embodiment of the invention.

FIG. 3 shows a plot of a current and voltage relationship for arepresentative solar panel.

FIG. 4 shows a plot of a power and voltage relationship for a similarpanel.

FIG. 5 shows one type of dual mode power conversion circuit such asmight be used in embodiments of the invention.

FIG. 6 shows an embodiment of the invention with series connected panelsand a single grid-tied inverter configuration.

FIGS. 7A and 7B show plots of solar panel output operational conditionsfor differing temperatures and output paradigms.

FIG. 8 shows a plot of losses by topology and range for traditionalapproach as compared to the present invention.

FIG. 9 shows a plot of combined protective and coordinated processconditions according to one operational embodiment of the invention.

FIG. 10 shows a prior art system with a traditional grid-tied inverter.

MODE(S) FOR CARRYING OUT THE INVENTION

As mentioned above, the invention discloses a variety of aspects thatmay be considered independently or in combination with others. Initialunderstanding begins with the fact that one embodiment of a powerconditioner according to the present invention may provide analternative process converter, a dual mode photovoltaic converter, avery high efficiency photovoltaic converter, or a multimodalphotovoltaic converter, all perhaps with the inclusion of maximum powerpoint tracking (MPP or MPPT) aspects. Such elements may presentalternative process conversion, dual mode photovoltaic conversion, ahighly efficient method of solar energy power conversion, etc.Embodiments may include operational boundaries such as for outputvoltage, output current, and perhaps even, output power. Each of theseshould be understood from a general sense as well as through embodimentsthat display initial applications for implementation. Some initialbenefits of each of these aspects are discussed individually and incombination in the following discussion as well as how each represents aclass of topologies, rather than just those initially disclosed.

FIG. 1 shows one embodiment of a solar energy power system illustratingthe basic solar conversion principles of the present invention. Asshown, it involves a solar energy source (1) feeding into a highefficiency photovoltaic DC-DC power converter (4) providing a convertedoutput such as a photovoltaic DC power output to a photovoltaic DC-ACinverter (5) that may provide a photovoltaic AC power output perhaps toultimately interface with a grid (10). As may be appreciated, the solarenergy source (1) may be a solar cell, a solar panel, or perhaps even astring of panels. Regardless, the solar energy source (1) may provide(and accomplish the step of creating) a DC photovoltaic output (2). Thishigh voltage, highly varying DC photovoltaic output (2) may serve as(and accomplish the step of establishing the output as) a DC input (3)to a high efficiency photovoltaic DC-DC power converter (4).

The high efficiency photovoltaic DC-DC power converter (4) may have itsoperation controlled by a highly efficient capability generallyindicated as converter functionality control circuitry (8) which may beachieved by high efficiency photovoltaic converter control circuitry. Asone of ordinary skill in the art should well appreciate, this converterfunctionality control circuitry (8) may be embodied as true circuitryhardware or it may be firmware or even software to accomplish thedesired control and would still fall within the meaning of a converterfunctionality control circuitry (8). Similarly, the high efficiencyphotovoltaic DC-DC power converter (4) should be considered to representphotovoltaic DC-DC power conversion circuitry. In this regard it islikely that hardware circuitry is necessary, however combinations ofhardware, firmware, and software should still be understood asencompassed by the circuitry term.

As illustrated in FIG. 1, the various elements may be connected to eachother. Direct connection is but one manner in which the various elementsmay be responsive to each other, that is, some effect in one maydirectly or indirectly cause an effect or change in another. Byreferring to an item connected to another item, it should be understoodthat the connection may be direct or indirect, that intermediateelements or components may be included, and even that one element may beachieved by a collection of components if desired. The high efficiencyphotovoltaic DC-DC power converter (4) may act to convert its input andthus provide (and accomplish the step of establishing) a converted DCphotovoltaic output (6) such as a photovoltaic DC power output which mayserve as an input to a photovoltaic DC-AC inverter (5) which may be of avariety of designs and brands. This DC-AC inverter (5) may be atraditional inverter for grid output for any system and may or may notbe included in embodiments of the solar energy power system and the highefficiency photovoltaic DC-DC power converter (4) may be provided aloneor in combination with an entire system. If included, the overall systemmay present a high efficiency solar energy power conversion system andif with an inverter capability, the system may serve to accomplish thestep of perhaps traditionally inverting the DC power or the DCphotovoltaic input into a high power inverted AC (7) such as an invertedAC photovoltaic power output (7) that can be used by, for example, atpower levels such as for a power grid (10) through some connectiontermed an AC power grid interface (9). In this manner the system maycreate a DC photovoltaic output (6) which may be established as an inputto some type or brand of DC-AC inverter such as a traditionalphotovoltaic DC-AC inverter (5) (e.g., an inverter that has no unusualsystem requirements such as shunt regulation or the like). This step ofinverting an input should be understood as encompassing creation of anysubstantially alternating signal from any substantially unidirectionalcurrent flow signal even if that signal is not itself perfectly, or evensubstantially, steady.

As show in FIGS. 2 and 6, individual solar energy sources (1)—whether ata cell, panel, or module level—may be established as a plurality of suchsources, each having their own DC photovoltaic output. These may becombined to create a series of electrically connected sources, perhapsto present a series string for solar power energy power conversion. Suchcombinations may be responsive through either series or parallelconnections. As shown in a series arrangement in FIGS. 2 and 6, theconnected plurality may form a string of electrically connected itemsperhaps such as a string of electrically connected solar panels (11). Asmay be easily appreciated, this string of electrically connected solarpanels (11) may accomplish the step of creating a DC photovoltaic outputfrom a plurality of solar panels. As shown in FIG. 2, each of thesestrings may be a component to a much larger combination perhaps forminga photovoltaic array (12) or even a sea of combined solar energysources. By either physical or electrical layout, certain of thesecells, panels, or strings may be adjacent in that they may be exposed tosomewhat similar electrical, mechanical, environmental, solar, orinsolative exposure conditions. In situations where large arrays areprovided, it may be desirable to include a high voltage DC-AC solarpower inverter perhaps with a three phase high voltage inverted ACphotovoltaic output as schematically illustrated in FIG. 2.

As illustrated for an electrically serial combination, output may becombined so that their voltages may add whereas their currents may beidentical. Conversely, electrically parallel combinations may exist.FIGS. 2 and 6 illustrate embodiments that are connected to accomplishserially combining or serially connecting items such as the converted DCphotovoltaic outputs (6) of each to create a higher voltage converted DCphotovoltaic input to a DC-AC inverter (5). As discussed below,embodiments can include a plurality of series connected high efficiencyswitchmode photovoltaic DC-DC converters, these converters may besubstantially power isomorporphic switchmode photovoltaic voltage (orimpedance) converters and perhaps the step of individually substantiallypower isomorphically converting each said high voltage, highly varyingDC photovoltaic outputs, or utilizing a plurality of series connectedsubstantially power isomorphic switchmode photovoltaic voltageconverters, each independently responsive to one of said plurality ofsolar panels. Such may be accomplished while maintaining maximum powerpoint operation. As shown, these serial connections may be of theconverted DC photovoltaic outputs (6) which may then create a convertedDC photovoltaic output (13) which may serve as a converted DCphotovoltaic input (14) to some type or brand of photovoltaic DC-ACinverter (5) or other load. Again, each solar power source (1) may be atthe cell, panel, string, or even array level. As would be wellunderstood, parallel connections and the step of parallel connectingconverters or their outputs could be accomplished as well.

As mentioned above relative to the MPPT aspect, circuitry and systemscan be configured to extract as much power as possible from the solarpower sources (1). Electrically, this is accomplished by achievingoperation to operate at one or more solar cell, panel, or string'smaximum power point (MPP) by MPP circuitry or maximum power pointtracking (MPPT). Thus, in embodiments, a solar power system according tothe invention may include: an MPPT control circuit with a powerconversion circuit. Significant to embodiments of the invention is thefact that by unique photovoltaic DC-DC converter circuitry, highefficiency conversion can be achieved with while accomplishing MPPT.Embodiments may even include range limiting circuitry as discussedlater.

The aspect of maximum power point is illustrated by reference to FIGS. 3and 4 and the Maximum Power Point Tracking (MPPT) circuit may beconfigured to find the optimum point for extracting power from a givenpanel or other solar energy source (1). This may be accomplished bymaximum photovoltaic power point controlling the switch elements. Asbackground, it should be understood that a panel such as may be measuredin a laboratory may exhibit the voltage and current relationshipsindicated in FIG. 3. Current in Amps is on the vertical axis. Voltage involts is on the horizontal axis. One can multiply the voltage times thecurrent to derive power. This is shown in FIG. 4 with power now on thevertical axis. The goal of an embodiment with an MPPT circuit as usedhere may be to apply an appropriate load resistance or more preciselyimpedance to a panel such that the panel may operate to provide its peakpower. Of course, as the figures illustrate, this results in convertingthe voltage derived from the panel. One can see graphically that themaximum power point on this panel under the measurement conditionsoccurs when the panel produces approximately 15 volts and 8 amperes.This may be determined by a maximum photovoltaic power point converterfunctionality control circuitry (15) which may even be part or all ofthe modality of operation of the converter functionality controlcircuitry (8). As shown in FIG. 2, this can be achieved by a pluralityof high efficiency photovoltaic converter control circuitriescontrolling each of the plurality of high efficiency photovoltaic DC-DCpower converters (4). These may include a plurality of individuallypanel dedicated maximum photovoltaic power point converter functionalitycontrol circuitries. In this fashion, the converter or the step ofconverting may provide a maximum photovoltaic power point modality ofphotovoltaic DC-DC power conversion or the step of maximum photovoltaicpower point converting and this may be accomplished as a step ofindividual dedicated maximum photovoltaic power point converting a DCphotovoltaic input from each of said plurality of solar panels. Asmentioned below, this may be accomplished by switching and perhaps alsoby duty cycle switching, and as such the system may accomplish maximumphotovoltaic power point duty cycle switching or the step of maximumphotovoltaic voltage determinatively duty cycle switching, and mayinclude maximum photovoltaic power point converter control duty cycleswitching circuitry.

As one skilled in the art would appreciate, there are numerous circuitconfigurations that may be employed to derive MPP information. Some maybe based on observing short circuit current or open circuit voltage.Another class of solutions may be referred to as a perturb and observe(P&O) circuit. The P&O methods may be used in conjunction with atechnique referred to as a “hill climb” to derive the MPP. As explainedbelow, this MPP can be determined individually for each source, foradjacent sources, or for entire strings to achieve best operation. Acombined system embodiment may utilize individual panel (understood toinclude any source level) dedicated maximum photovoltaic power pointconverter functionality control circuitries (16).

Regardless of whether individually configured or not, in one P&O method,an analog circuit could be configured to take advantage of existingripple voltage on the panel. Using simple analog circuitry it may bepossible to derive panel voltage and its first derivative (V′), as wellas panel power and its first derivative (P′). Using the two derivativesand simple logic it may be possible to adjust the load on the panel asfollows:

TABLE 1 V′ Positive P′ Positive Raise MPP V′ Positive P′ Negative LowerMPP V′ Negative P′ Positive Lower MPP V′ Negative P′ Negative Raise MPP

There may be numerous other circuit configurations for findingderivatives and logic for the output, of course. In general, a powerconditioner (17) may include power calculation circuitry (firmware, orsoftware)(21) which may even be photovoltaic multiplicative resultantcircuitry (22). These circuitries may act to effect a result or respondto an item which is analogous to a power indication (even if not theprecise mathematical resultant of a V*I multiplication function). Thismay of course be a V*I type of calculation of some power parameters andthe system may react to either raise or lower itself in some way toultimately move closer to and eventually achieve operation at an MPPlevel. By provided a capability and achieving the step of calculating aphotovoltaic multiplicative power parameter, the system can respond tothat parameter for the desired result.

In embodiments where there is a series string of power conditioners (17)or the like, the current through each PC output may be the same but theoutput voltage of each PC may be proportional to the amount of power itspanel makes. Consider the following examples to further disclose thefunctioning of such embodiments. Examine the circuit of FIG. 6 andcompare it to panels simply connected in series (keep in mind that thesimple series connection may have a reverse diode across it). First,assume there are four panels in series each producing 100 volts and 1amp feeding an inverter with its input set to 400 volts. This gives 400watts output using either approach. Now consider the result of one panelmaking 100 volts and 0.8 amps (simulating partial shading—less lightsimply means less current). For the series connection, the 0.8 ampsflows through each panel making the total power 400×0.8=320 watts. Nowconsider the circuit of FIG. 6. First, the total power would be 380watts as each panel is making its own MPP. And, of course, the currentfrom each Power Conditioner must be the same as they are after all stillconnected in series. But with known power from each PC, the voltage maybe calculated as:

3V+0.8V=400 volts, where V is the voltage on each full power panel.

Thus, it can be seen that in this embodiment, three of the panels mayhave 105.3 volts and one may have 84.2 volts (thus presenting avariation of about 21.1 volts and a variation of about 1.25:1).

Further, in FIG. 6 it can be understood that in some embodiments, anadditional benefit may be derived from the inclusion of individual powercontrol. In such embodiments, a power block may be considered as a groupof PV panels with power conversion and MPP per panel configurations. Assuch they may adapt their output as needed to always maintain maximumpower from each and every power block. If adapted to be used with such astring of power blocks, the system may even operate with a varyingvoltage on its output.

The advantage of this type of a configuration is illustrated from asecond example of MPP operation. This example is one to illustrate whereone panel is shaded such that it can now only produce 0.5 amps. For theseries connected string, the three panels producing 1 amp may completelyreverse bias the panel making 0.5 amps causing the reverse diode toconduct. There may even be only power coming from three of the panelsand this may total 300 watts. Again for an embodiment circuit ofinvention, each PC may be producing MPP totaling 350 watts. The voltagecalculation would this time be:

3V+0.5V=400 volts

In this instance, the three panels may have a voltage of 114.2 volts andthe remaining one may have half as much, or 57.1 volts (thus presentinga variation of about 57.1 volts and a variation of about 2:1). (For apanel producing as low as the 15 volts mentioned above up to 114.2volts, such would present a variation of about 99.2 volts and avariation of about 7.6:1). Output voltage can be seen as proportional toPV panel output power thus yielding a better result.

These are basic examples to illustrate some advantages. In an actual PVstring today there may be many PV panels in series, and usually none ofthem make exactly the same power. Thus, many panels may become backbiased and most may even produce less than their individual MPP. Thiscan be overcome by embodiments of the present invention that utilizeMPPT aspects. In FIG. 6 there is shown a power converter for takingpower from a panel string and powering the grid. As discussed below,such configuration may need voltage limits and/or protection perhaps bysetting operational boundaries.

A power conditioner (17) may be configured to always extract the maximumpower from a PV panel. According to embodiments of the invention, thisand other aspects may be accomplished by an impedance (or voltage)transformation capability provided through the power conditioner (17),the high efficiency photovoltaic DC-DC power converter (4), or theconverter functionality control circuitry (8). These may includephotovoltaic load impedance increase converter functionality controlcircuitry and photovoltaic load impedance decrease converterfunctionality control circuitry. Elements may act to change the highvoltage, highly varying outputs and as such may include photovoltaicvoltage increase converter functionality control circuitry, (and thestep of providing, or perhaps feeding through, at least one photovoltaicvoltage increase modality of photovoltaic DC-DC power conversion), aswell as photovoltaic voltage decrease converter functionality controlcircuitry (and the step of providing, or perhaps feeding through, atleast one photovoltaic voltage decrease modality of photovoltaic DC-DCpower conversion perhaps responsive to the voltage increase modality).Such may act to transform the impedance or voltage of the individual orgroup power delivery as needed to maintain the MPP. The system may thuscause a variation in the voltage of each panel as it achieves maximumoutput for each. Based on topology of the system, this may beaccomplished perhaps with a constant or common current so the seriesstring is at maximum power. In embodiments, the invention may beconfigured to increase or decrease the load impedance or voltage for onepanel and may even provide a fixed voltage if desired.

As suggested above, a photovoltaic impedance or voltage transformationmodality of photovoltaic DC-DC power conversion can be accomplished byphotovoltaic impedance or voltage transformation power conversioncontrol circuitry or by including elements such as: photovoltaicimpedance increase photovoltaic DC-DC power conversion circuitry,photovoltaic impedance decrease photovoltaic DC-DC power conversioncircuitry, photovoltaic voltage increase photovoltaic DC-DC powerconversion circuitry, and/or photovoltaic voltage decrease photovoltaicDC-DC power conversion circuitry. A preferred embodiment of switching orswitchmode photovoltaic impedance or voltage transformation photovoltaicDC-DC power converter is shown in FIG. 5. As may be appreciated, theswitches included may be controlled by converter functionality controlcircuitry (8) for duty cycle switching, that is switching at periodic(even if not constant or if having varying periods) times to accomplisha variety of goals. This switching can occur in a variety of ways. Theremay also be variations in the method for switching from one mode toanother. For example, if a minimum pulse width is set, it may bepossible to further reduce the energy or alter the impedance or altervoltage by going to a burst mode as discussed below. If a minimum dutycycle is set to 2%, it is possible to get 0.2% energy transfer by usingoccasional bursts of the 2% duty cycle with a burst duty cycle of say10%. Much of this may be achieved by frequency altered switching orother control of differing switches. Thus embodiments may provide switchfrequency alteration switching photovoltaic power conversion controlcircuitry such as switch frequency alteration duty cycle switchingphotovoltaic power conversion control circuitry. This can give thepossibility of a smooth transformation from one mode (such as a voltageor impedance change) to another while providing high efficiency duringthe transformation or conversion.

A goal in switching may include the maximum power point operationdiscussed above as well as a number of modalities as discussed below.Modalities of duty cycle and other control can be highly efficient andso embodiments can accomplish individually high efficiency conversionduty cycle controlling operation of the switch elements. Further, someof these modalities may even be slaved such that one takes precedence ofone or another at some point in time, in some power regime, or perhapsbased on some power parameter to achieve a variety of modalities ofoperation. These may include slaved maximum photovoltaic power pointconverter functionality control circuitry, slavedly individual paneldedicated maximum photovoltaic power point DC-DC converting, slavedphotovoltaic inverter operating condition converter functionalitycontrol circuitry, slaved photovoltaic load impedance increase converterfunctionality control circuitry, slaved photovoltaic load impedancedecrease converter functionality control circuitry, slaved photovoltaicvoltage increase converter functionality control circuitry, and slavedphotovoltaic voltage decrease converter functionality control circuitry.Again, some of these modalities are discussed later. In the context ofimpedance or voltage transformation or conversion, however, there may bephotovoltaic impedance or voltage transformation duty cycle switching,and such may be controlled by photovoltaic impedance or voltagetransformation duty cycle switch control circuitry (again understood asencompassing hardware, firmware, software, and even combinations ofeach).

With reference to the particular embodiments illustrated in FIG. 5, itmay be understood that the high efficiency photovoltaic DC-DC powerconverter (4) may be operated to cause the photovoltaic impedance orvoltage to increase or decrease. These two alternative modes ofoperation (increasing and decreasing) may even be exclusive in thateither one or the other may exist at any point in time, even if suchoperations change over time. As such, embodiments may includephotovoltaic impedance increase (or voltage increase, the effects aresimilar) photovoltaic DC-DC power conversion circuitry (19) and perhapsphotovoltaic impedance decrease (or voltage decrease) photovoltaic DC-DCpower conversion circuitry (20). Regardless of the mode employed,embodiments may accomplish alternating between a first modality ofphotovoltaic DC-DC power conversion and a second modality. Examples of apreferred circuit is illustrated in FIG. 5 where it can be consideredthat a first part (20) of the high efficiency photovoltaic DC-DC powerconverter (4) acts in one way (to increase impedance and increasevoltage in FIG. 5) and a second part (19) of the high efficiencyphotovoltaic DC-DC power converter (4) acts in the other way (todecrease impedance and decrease voltage in FIG. 5). Thus it can be seenthat modes of operation in the high efficiency photovoltaic DC-DC powerconverter (4) may be opposing in that one accomplishes an effect and theother accomplishes a contrary effect and that embodiments may includeopposite modality photovoltaic DC-DC power conversion circuitries.Embodiments of the system may provide at least one photovoltaicimpedance or voltage increase modality of photovoltaic DC-DC powerconversion and at least one photovoltaic impedance or voltage decreasemodality of photovoltaic DC-DC power conversion. As shown for theembodiment in FIG. 5, both of these modalities may be provided (orcontrol achieved) in one high efficiency photovoltaic DC-DC powerconverter (4) so that the high efficiency photovoltaic DC-DC powerconverter (4) may achieve the steps of photovoltaic load impedance orvoltage increasing and photovoltaic load impedance or voltagedecreasing. These may occur during the same time or at differing timesand may be slaved or not. At differing times, such elements may beconsidered disjunctive so that in alternative operation one operateswhen the other does not and visa versa. Such may also be substantiallydisjunctive so that for only power conversion insignificant periods dothey both actually or appear to operate in similar timeframes. Thus thesystem may include substantially disjunctive impedance transformationphotovoltaic power conversion control circuitry. Through the powerconditioner (17) configuration and design the system may provideswitching or other capability and, if applicable, control circuitry thatmay provide the desired effect. An aspect that may aid in the ability toachieve the unusually high efficiencies is the fact that the highefficiency photovoltaic DC-DC power converter (4) can be configured toincrease voltage and then decrease voltage. As may be appreciated by aperson of ordinary skill in the art, since the dominant losses can beresistance based, first increasing voltage can be understood for itsbeneficial effect relative to efficiency. For example, consider thatwhen existing for a set level of power (such as that panel's thenexisting MPP), increasing voltage has the effect of decreasing current.From a basic perspective, resistance losses are mathematically expressedas I²R. Thus the dominant loss can be considered as a function ofcurrent squared. By intermediately (or initially) decreasing current orequivalently increasing voltage, this loss can be minimized and theoverall conversion operation can be accomplished more efficiently thanfor a converter that first decrease voltage and then increases it.

Referring again to the embodiment shown in FIG. 5, it can be seen thatsome embodiments may utilize one or more switches that may be controlledby photovoltaic switch control circuitry (23) and thus the powerconditioner (17) may be of a switchmode character. In the embodimentsshown, these switches are designated T21-T24. In some embodiments, theseswitches may be semiconductor switches and this may facilitate lowerlosses and higher efficiency. Furthermore, the switches and connectionsmay be configured to provide one or more photovoltaic power seriesswitch elements (24), perhaps dual or a first and second photovoltaicpower interrupt switch elements (respectively T21 and T23), and dual orone or more photovoltaic power shunt switch elements (25), perhaps afirst and second photovoltaic power shunt switch elements (respectivelyT22 and T24). As may be appreciated the photovoltaic power series switchelements (24) may be connected as shown and may provide one or morelocations at which the transmission of photovoltaic power may beinterrupted (the act of interrupting) and the photovoltaic power shuntswitch elements (25) may be connected as shown and may provide one ormore locations at which the transmission of photovoltaic power may beshunted (the act of shunting) to ground, another power path, or thelike. As shown in FIG. 5, embodiments may have particular connectionarrangements and may even include one or additional capacitances orcapacitor elements. These may include a parallel capacitance, perhapsreferred to as a common capacitor C3 connected as shown. In thisparticular embodiment, the first photovoltaic power interrupt switchelement (T21) has a first input end (31) and a first output end (32)configured as shown. Similarly, the second photovoltaic power interruptswitch element (T23) has a second input end (33) and a second output end(34) configured as shown. Also included may be a first parallelcapacitance (C1) and a first series inductance (L1) as well as a secondparallel capacitance (C2) and a second series inductance (L2). The firstseries inductance (L1) may be connected to the first input end (31) ofthe first photovoltaic power interrupt switch element, and the firstparallel capacitance (C1) may be connected to the input side of thefirst series inductance (L1). Similarly, the second series inductance(L2) may be connected to the second output end (34) of the secondphotovoltaic power interrupt switch element, and the second parallelcapacitance (C2) may be connected to the output side of the secondseries inductance (L2).

As the illustration in FIG. 5 shows, embodiments may include not justone switch, not just one series and shunt switch, but even pairs ofseries pathed and shunt pathed semiconductor (or other) switches. Thus,the interrupting and the shunting can occur at least two separatesemiconductor switch locations. Obviously, this example is configured tomore simply illustrate each of the switching, interrupting, shunting,and pairing concepts, however, it should be understood that more complexconfigurations are possible. As with many circuitry aspects, somedesigns may even be arranged to elusively achieve the same effect; thesewould still fall within the scope of the present invention, of course.

As may be easily understood from the above, embodiments may accomplishhigh efficiency switching a first photovoltaic power interrupt switchelement, high efficiency switching a second photovoltaic power interruptswitch element (perhaps connected as shown), high efficiency switching afirst photovoltaic power shunt switch element, high efficiency switchinga second photovoltaic power shunt switch element (perhaps connected asshown), capacitively storing parallel energy in a parallel capacitance(perhaps connected as shown), and high efficiency conversion duty cyclecontrolling operation of said first and second photovoltaic powerinterrupt switch elements and said first and second photovoltaic powershunt switch elements.

As may be appreciated from just the initially discussed modes ofoperation, namely, the modes of increasing and, perhaps alternatively,decreasing photovoltaic load impedance or voltage, systems according toembodiments of the present invention may provide a high efficiencyphotovoltaic DC-DC power converter (4) that serves as a multimodalphotovoltaic DC-DC power converter perhaps controlled by multimodalconverter functionality control circuitry (26) in that it has more thanone mode of operation. These modes may include, but should be understoodas not limited to, photovoltaic impedance or voltage increasing andphotovoltaic impedance or voltage decreasing; several other modes arediscussed below. In general, the aspect of multimodal activityencompasses at least processes where only one mode of conversion occursat any one time. Impedance, or any other factor, may or may not beincreased and then decreased in the same process regardless of thedesired outcome. Only a single method of conversion is used, perhapswith a singular integration.

Thus, a power conditioner (17) may provide at least a first modality andsecond modality photovoltaic DC-DC power conversion circuitry, DC-DCpower converter, or DC-DC power conversion. Further, as can beunderstood in an MPP context of increasing or decreasing photovoltaicload impedance, the multimodal photovoltaic DC-DC power converter orperhaps multimodal converter functionality control circuitry (26) mayrespond to one or more photovoltaic power condition, perhaps such as theV*I multiplicative factor, a voltage level, a current level, or someother perhaps signal indicated or calculated set point. In so offeringthe capability of more than one mode of conversion operation (eventhough not necessarily utilized at the same time), or in offering thecapability of changing modes of operation, the system may accomplish thestep of multimodally converting a DC photovoltaic input into a convertedphotovoltaic DC output. Similarly, by offering the capability ofcontrolling to effect more than one mode of conversion operation (again,whether or not utilized at the same time), or in controlling to changemodes of operation, the system may accomplish the step of multimodallycontrolling operation of a high efficiency photovoltaic DC-DC powerconverter (4).

Embodiments may include even two or more modes of operation and thus maybe considered a dual mode power conversion circuit or dual modeconverter. The dual mode nature of this circuit may embody a significantbenefit and another distinction may be that most DC/DC converters areoften intended to take an unregulated source and produce a regulatedoutput. In this invention, the input to the DC/DC converter may beregulated to be at the PV panel MPP. The power taken from the PV panelmay be transformed to whatever impedance or voltage is needed in theoutput connection to be able to satisfy the input MPP requirement evenwithout regarding to output.

In the case of the impedance being changed such that the output voltageis lower than the input voltage, T21 can be forced to be in a continuousconduction state and T22 in a non-conducting state with T23 and T24operated in a switchmode duty cycle state. This duty cycle of operationcan be synchronous in that the transistor T24 may be switchedsynchronously with T23 (with inverted duty cycle). T24 may be a lowR_(DS(ON)) FET having much lower losses than a diode in this location.By such synchronous operation this circuit can have extremely highefficiency as mentioned more generally below. A concern can exist forthis circuit in that current passes through an additional transistor,T21, but this transistor can have low loss as it is not switching.

Similarly, in the case of the impedance being changed such that theoutput voltage is higher than the input voltage, T23 can be forced to bein a continuous conduction state and T24 in a non-conducting state withT21 and T22 operated in a switchmode duty cycle state. This duty cycleof operation can be synchronous in that the transistor T22 may beswitched synchronously with T21 (with inverted duty cycle). T22 may be alow R_(DS(ON)) FET having much lower losses than a diode in thislocation. By such synchronous operation this circuit can have extremelyhigh efficiency as mentioned more generally below. A concern can existfor this circuit in that current passes through an additionaltransistor, T23, but this transistor can have low loss as it is notswitching. This, second mode (if exclusively operating) for the circuitshown in FIG. 5 shows that operation is possible where the impedanceneeds to be altered such that the output voltage is higher than theinput voltage. As mentioned, now, T23 may be switched to a continuousconduction state. T24 may be non-conducting. Now transistors T21 and T22may be controlled in a switchmode manner. One may see the same ideasapply. First, all switches are transistors having low on-state loss.Secondly the boost section may be operated with high efficiency with theonly additional loss due to the dual mode capability in the on-stateloss of transistor T23. This circuit can also make use of a parallelcapacitance, perhaps referred to as a common capacitor C3 saving size,space and cost.

Interesting, and as also discussed below, while in prior art efficiencywas sometimes shown to be less than 91%, this circuit accomplishes theneeded DC-DC conversion function while operating even above 98% and atlevels as high as 99.2% and even line loss efficiency. When connected toa solar panel or an array of solar panels this efficiency difference canbe of paramount importance.

As mentioned briefly above, there may be alternating modes of operationand the system may vacillate (and achieve vacillatory conversion modes)between differing modes based upon a parameter or other indication orcalculation. In embodiments where one mode or another is substantiallyexclusively activated, a power conditioner (17) or other system elementmay provide an alternative mode photovoltaic power converterfunctionality control (27). It may exclusively switch between modes atleast some times. These modes may be modes of conversion and so thesystem may provide a vacillatory method of creating solar power. Asindicated above, these modes may be opposing or opposing modalities,substantially disjunctive, or otherwise, and the system may includeopposite modality photovoltaic DC-DC power conversion circuitries.

In exclusively controlling a particular operational mode, systems maydisable an unused mode. This can be important, for example, to achievethe higher levels of efficiency mentioned below or the like. Referringto the examples illustrated in the context of photovoltaic impedancetransformation in FIG. 5, it can be understood how embodiments of theinvention can act to disable a mode of photovoltaic DC-DC powerconversion perhaps through operation or control of the DC-DC converter,or operation at least some times and thus the system can provide disablealternative mode photovoltaic power conversion control circuitry (28).As discussed with respect to switch operation in the context of MPP,above, one or more switch(es), perhaps such as the photovoltaic powershunt switch element (25), one of the photovoltaic power series switchelements (24), or otherwise may be disabled during an operation. Thismay provide a capability to compare modes of operation or, perhaps mostimportantly, may permit highly efficient operation previously notbelieved achievable. Thus embodiments may provide photovoltaic disablemode converter functionality control circuitry.

An aspect of operational capability that can afford advantage is thecapability of embodiments of the invention to accommodate differingoperating conditions for various solar sources or panels. As shown inFIGS. 7A and 7B, voltages of operation for maximum power point can varybased upon whether the solar source is experiencing hot or coldtemperature conditions. By permitting MPP to be accommodated throughimpedance or voltage transformation apart from any voltage constraint,embodiments according to the invention may provide expansive panelcapability. This may even be such that the converter is effectively afull photovoltaic temperature voltage operating range photovoltaic DC-DCpower converter whereby it can operate at MPP voltages as high as thatfor the MPP in a cold temperature of operation as well as the MPPvoltages as low as that for the MPP in a hot temperature of operation.Thus, as can be understood from FIGS. 7A and 7B, systems can providesolar energy source open circuit cold voltage determinative switchingphotovoltaic power conversion control circuitry and solar energy sourcemaximum power point hot voltage determinative switching photovoltaicpower conversion control circuitry. It can even achieve fullphotovoltaic temperature voltage operating range converting. This may beaccomplished through proper operation of the switch duty cycles andsystems may thus provide solar energy source open circuit cold voltagedeterminatively duty cycle switching and solar energy source maximumpower point hot voltage determinatively duty cycle switching.

Further, viewing hot and cold voltages as perhaps the extremeconditions, similarly it can be understood how the system mayaccommodate varying amount of insolation and thus there may be providedinsolation variable adaptive photovoltaic converter control circuitrythat can extract MPP whether a panel is partially shaded, even ifrelative to an adjacent panel. Systems and their duty cycle switchingmay be adaptable to the amount of insolation and so the step ofconverting may be accomplished as insolation variably adaptivelyconverting. This can be significant in newer technology panels such ascadmium-telluride solar panels and especially when combining outputsfrom a string of cadmium-telluride solar panels which can have broaderoperating voltages.

As mentioned earlier, an aspect of significant importance is the levelof efficiency with which the converter operates. This is defined as thepower going out after conversion over the power coming in beforeconversion. A portion of the efficiency gain is achieved by usingswitchmode operation of transistor switches, however, the topology isfar more significant in this regard. Specifically, by the operation ofswitches and the like as discussed above, the system can go far beyondthe levels of efficiency previously thought possible. Embodiments caninclude one or more substantially power isomorporphic switchmodephotovoltaic voltage (or impedance) converters. This can include thestep of substantially power isomorphically converting. It can evenprovide a substantially power isomorphic photovoltaic DC-DC powerconversion that does not substantially change the form of power intoheat rather than electrical energy by providing as high as about 99.2%efficiency. This can be provided by utilizing substantially powerisomorphic photovoltaic converter functionality, by substantially powerisomorphic photovoltaic converter functionality control circuitry, andby a substantially power isomorphic photovoltaic impedance converter andby controlling operation of the switches so that there is limited lossas discussed above. Such operation can be at levels of from 97, 97.5,98, 98.5 up to either 99.2 or essentially the wire transmission lossefficiency (which can be considered the highest possible). Thusembodiments may achieve high efficiency conversion duty cyclecontrolling of the operation of the switches, and may include 97%efficient photovoltaic conversion circuitry, 97.5% efficientphotovoltaic conversion circuitry, 98% efficient photovoltaic conversioncircuitry, 98.5% efficient photovoltaic conversion circuitry, 99.2%efficient photovoltaic conversion circuitry, and solar power convertingwith at least about 97% efficiency, solar power converting with at leastabout 97.5% efficiency, solar power converting with at least about 98%efficiency, solar power converting with at least about 98.5% efficiency,solar power converting with at least about 99.2% efficiency, and solarpower converting up to about wire transmission loss efficiency.

One aspect that contributes to such efficiency is the fact that minimalamounts of energy are stored during the conversion process. As shown inFIG. 5, such embodiments may include one or more parallel capacitancesand one or more series inductances. These may be used to store energy atleast some times in the operation of converting. It may even beconsidered that full energy conversion is not accomplished, only theamount of conversion necessary to achieve the desired result. Thusembodiments may serve as a low energy storage photovoltaic DC-DC powerconverter and even a partial energy storage photovoltaic DC-DC powerconverter. In situations where the voltage in and the voltage out arenearly identical and thus the converter achieves unity conversion, thereis even substantially no change in energy storage and so the system mayhave embodiments that are considered a substantially constant energystorage photovoltaic DC-DC power converter. Cycle-by-cycle energystorage may also be proportional (whether linearly, continuously, ornot) to a voltage difference in conversion. Energy stored, perhaps inthe inductor may also be proportional to a duty cycle for one or moreswitches. Part of the efficiency can also be considered as existing as aresult of the fact that during operation some switches may remain staticand either open or closed. Thus embodiments may provide static switchalternative mode photovoltaic power conversion control circuitry andsimilarly, static switch converting. It may also provide fractionalswitch element control circuitry.

Switches can be controlled in a variable duty cycle mode of operationsuch that frequency of switching alters to achieve the desired facet.The converter functionality control circuitry (8) may thus serve asphotovoltaic duty cycle switch control circuitry. The duty cycleoperations and switching can achieve a variety of results, from servingas photovoltaic impedance or voltage transformation (or increase ordecrease) duty cycle switching, to other operations. Some of these mayeven be due to considerations apart from the conversion aspect that canbe considered the primary purpose of the high efficiency photovoltaicDC-DC power converter (4).

While in theory or in normal operation the described circuits work fine,there can be additional requirements for a system to have practicalfunction. For example the dual mode circuit as described could go toinfinite output voltage if there were no load present. This situationcan actually occur frequently. Consider the situation in the morningwhen the sun first strikes a PV panel string with power conditioners(17). There may be no grid connection at this point and the invertersection may not draw any power. In this case the power conditioner (17)might in practical terms increase its output voltage until the inverterwould break. Rather than just dump this energy, the inverter could haveovervoltage protection on its input adding additional power conversioncomponents or, the power conditioner may simply have its own internaloutput voltage limit. For example if each power conditioner (17) couldonly produce 100 volts maximum and there was a string of ten PCs inseries the maximum output voltage would be 1000 volts. This outputvoltage limit could make the grid-tied inverter less complex or costlyand is illustrated in FIG. 7A as a preset overvoltage limit. Thusembodiments can present maximum voltage determinative switchingphotovoltaic power conversion control circuitry and maximum photovoltaicvoltage determinative duty cycle switching (as shown in FIG. 7A as thepreset overvoltage limit) or maximum voltage determinative duty cycleswitching photovoltaic power conversion control circuitry. This can beinverter specific.

A maximum output current limit may also be useful and is illustrated inFIG. 7A as the preset overcurrent limit. This is less straightforwardand is related to the nature of a PV panel. If a PV panel is subjectedto insufficient light its output voltage may drop but its output currentmay not be capable of increasing. There can be an advantage to onlyallowing a small margin of additional current. For example, this same100 watt panel which has a 100 volt maximum voltage limit could alsohave a 2 amp current limit without limiting its intended use. This mayalso greatly simplify the following grid tied inverter stage. Consideran inverter in a large installation which may need or use the moretraditional approach of a crowbar shunt front end for protection. If theoutput of a PC could go to 100 amps the crowbar would have to handleimpractical currents. This situation would not exist in a non PCenvironment as a simple PV panel string could be easily collapsed with acrowbar circuit. This current limit circuit may only be needed with a PCand it may be easily achieved by duty cycle or more precisely switchoperation control. Once a current limit is included another BOS savingsmay be realized. Now the wire size for interconnect of the series stringof PCs may be limited to only carry that maximum current limit. Here,slaved or not, embodiments can present maximum photovoltaic invertercurrent converter functionality control circuitry, photovoltaic inverteroperating condition controlling the photovoltaic DC-DC converter,photovoltaic inverter maximum current determinative switching,photovoltaic inverter maximum current determinative duty cycle switchingphotovoltaic power conversion control circuitry, photovoltaic invertermaximum current determinative duty cycle switch control circuitry,maximum photovoltaic inverter current controlling the photovoltaic DC-DCconverter, and photovoltaic inverter maximum current determinativelyduty cycle switching or the like.

Similarly, embodiments can present maximum photovoltaic inverter voltageconverter functionality control circuitry, photovoltaic inverter maximumvoltage determinative switching, photovoltaic inverter maximum voltagedeterminative duty cycle switch control circuitry, maximum photovoltaicvoltage determinative duty cycle switch control circuitry, andphotovoltaic inverter maximum voltage determinatively duty cycleswitching or the like.

One more system problem may also be addressed. In solar installations itmay occur on rare conditions that a panel or field of panels may besubjected to more than full sun. This may happen when a refractorysituation exists with clouds or other reflective surfaces. It may bethat a PV source may generate as much as 1.5 times the rated power for afew minutes. The grid tied inverter section must either be able tooperate at this higher power (adding cost) or must somehow avoid thispower. A power limit in the PC may be the most effective way to solvethis problem. In general, protection of some other element can beachieved by the converter. Embodiments can include aspects such asphotovoltaic converter operating condition controlling the photovoltaicDC-DC converter. This may even be a posterior or downstream element suchas the inverter and so the converter functionality control circuitry (8)may achieve controlling a posterior photovoltaic operating conditionthrough control of the photovoltaic DC-DC converter, as well asprotecting a posterior photovoltaic element through control of saidphotovoltaic DC-DC converter, and may serve to achieve photovoltaicinverter protection modality of photovoltaic DC-DC power conversion andmay be considered as photovoltaic inverter protection converterfunctionality control circuitry. Beyond protection, desirable inverteror other operating conditions can be achieved by the converter, thusembodiments may include photovoltaic inverter operating conditionconverter functionality control circuitry or photovoltaic converteroperating condition converter functionality control circuitry. These maybe simply coordinated in some manner such as by a photovoltaic inverteror posterior photovoltaic or other element coordinated modality orphotovoltaic inverter or posterior photovoltaic element coordinatedconverter functionality control circuitry, or posterior photovoltaicelement protection converter functionality control circuitry.Embodiments may accomplish controlling said photovoltaic DC-DC converterto coordinate with characteristics of a photovoltaic inverter, slavedlycontrolling a photovoltaic conversion modality through said photovoltaicDC-DC converter, and photovoltaic inverter slavedly controlling aphotovoltaic conversion modality through said photovoltaic DC-DCconverter, to name a few possibilites. There may also be embodimentsthat have small output voltage (even within an allowed output voltagerange). This may accommodate an inverter with a small energy storagecapacitor. The output voltage may even be coordinated with an inverter'energy storage capability.

As illustrated in FIGS. 7A, 7B, and 9, boundary conditions may be setsuch as the overcurrent limit and the overvoltage limit. Thus theconverter and/or its control circuitry may serve as photovoltaicboundary condition converter functionality control circuitry, mayachieve a photovoltaic boundary condition modality of photovoltaic DC-DCpower conversion, and may accomplish the step of controlling aphotovoltaic conversion boundary condition of the photovoltaic DC-DCconverter, as well as photovoltaic boundary condition controlling of theswitch elements.

Yet another mode of operation may be to make a value proportional (inits broadest sense) to some other aspect. For example, there can beadvantages to making voltage proportional to current such as to providesoft start capability or the like. Thus embodiments may be configuredfor controlling a maximum photovoltaic output voltage proportional to aphotovoltaic output current at least some times during the process ofconverting a DC input to a DC output. In general, this may provide softtransition photovoltaic power conversion control circuitry. And thesystem may include duty cycle control or switch operation that can beconducted so as to achieve one or more proportionalities between maximumvoltage output and current output or the like. Further, not only can anyof the above be combined with any other of the above, but each may beprovided in a slaved manner such that consideration of one modality issecondary to that of another modality.

A variety of results have been described above. These may be achieved bysimply altering the duty cycle of switches or by appropriatelycontrolling the switches in some regard. These can be accomplished basedon thresholds and so can provide threshold triggered alternative mode,threshold determinative, threshold activation, or threshold deactivationswitching photovoltaic power conversion control circuitry. Naturally,these may include threshold determinative duty cycle switchingphotovoltaic power conversion control circuitry, threshold determinativemode deactivation duty cycle switching photovoltaic power conversioncontrol circuitry, as well as threshold determinative mode activationduty cycle switching photovoltaic power conversion control circuitry. Aburst mode of operation perhaps such as when nearing a mode alterationlevel of operation may be provided and at such times frequency can behalved, opposing modes can be both alternated, and levels can be reducedas a change becomes incipient. Such can be provided by burst mode dutycycle switching photovoltaic power conversion control circuitry. Thiscan be transient as well. In these manners burst mode switchingphotovoltaic power conversion control circuitry and burst mode switchingcan be accomplished, as well as transient opposition mode photovoltaicduty cycle switch control circuitry, transiently operated oppositemodality photovoltaic DC-DC power conversion circuitries, and the stepof transiently establishing opposing switching modes.

As mentioned above, the PCs and high efficiency photovoltaic DC-DC powerconverters (4) may handle individual panels. They may be attached to apanel, to a frame, or separate. Embodiments may have convertersphysically integral to such panels in the sense that they are providedas one attached unit for ultimate installation. This can be desirablesuch as when there are independent operating conditions for separatesolar sources, and even adjacent solar sources to accommodate variationsin insolation, condition, or otherwise. Each panel or the like mayachieve its own MPP, and may coordinate protection with all others in astring or the like.

FIG. 10 illustrates one type of traditional photovoltaic DC-AC inverter(5) that may be used. Naturally as may be appreciated from the earliercomments enhanced inverters that need not control MPP and that arealternatively protected by the converter may be used. Inverters may evenhave a separate control input so that the input voltage is at a mostoptimal level, perhaps such as a singular sweet spot or the like asillustrated by the bold vertical line in FIG. 9. Although otherinventions by the present assignee address such aspects, they may beconsidered incidental to the converter invention described here. Thus atraditional inverter is shown in FIG. 10. This may merely provide aconnection to some type of AC power grid interface (9).

As the invention becomes more accepted it may be advantageous to permitcomparison with more traditional technologies. This can be achieved bysimple switch operation whereby traditional modes of operation can beduplicated or perhaps adequately mimicked. Thus embodiments may includea solar power conversion comparator (29) that can compare first andsecond modes of operation, perhaps the improved mode of an embodiment ofthe present invention and a traditional, less efficient mode. Thiscomparator may involve indicating some solar energy parameter for each.In this regard, the shunt switch operation disable element may behelpful. From this a variety of differences can be indicated, perhaps:solar power output differences, solar power efficiency differences,solar power cost differences, solar power insolation utilizationcomparisons, and the like.

By the above combinations of these concepts and circuitry, at least someof the following benefits may be realized:

-   -   Every PV panel may produce its individual maximum power. Many        estimates today indicate this may increase the power generated        in a PV installation by 20% or even more.    -   The grid tied inverter may be greatly simplified and operate        more efficiently.    -   The photovoltaic DC-DC converter may be greatly simplified and        operate more efficiently.    -   The Balance of System costs for a PV installation may be        reduced.

The circuitry, concepts and methods of various embodiments of theinvention may be broadly applied. It may be that one or more PCs perpanel may be used. For example there may be non-uniformities on a singlepanel or other reasons for harvesting power from even portions of apanel. It may be for example that small power converters may be used onpanel segments optimizing the power which may be extracted from a panel.This invention is explicitly stated to include sub panel applications.

This invention may be optimally applied to strings of panels. It may bemore economical for example to simply use of a PC for each string ofpanels in a larger installation. This could be particularly beneficialin parallel connected strings if one string was not able to produce muchpower into the voltage the remainder of the strings is producing. Inthis case one PC per string may increase the power harvested from alarge installation.

This invention is assumed to include many physical installation options.For example there may be a hard physical connection between the PC and apanel. There may be an interconnection box for strings in which a PC perstring may be installed. A given panel may have one or more PCsincorporated into the panel. A PC or converter may also be a stand-alonephysical entity.

All of the foregoing is discussed in the context of a solar powerapplication. As may be appreciated, some if not all aspects may beapplied in other contexts as well. Thus, this disclosure should beunderstood as supporting other applications of the converter regardlesshow applied and even whether applied as a power converter, impedanceconverter, voltage converter, or otherwise.

As can be easily understood from the foregoing, the basic concepts ofthe present invention may be embodied in a variety of ways. It involvesboth solar power generation techniques as well as devices to accomplishthe appropriate power generation. In this application, the powergeneration techniques are disclosed as part of the results shown to beachieved by the various circuits and devices described and as stepswhich are inherent to utilization. They are simply the natural result ofutilizing the devices and circuits as intended and described. Inaddition, while some circuits are disclosed, it should be understoodthat these not only accomplish certain methods but also can be varied ina number of ways. Importantly, as to all of the foregoing, all of thesefacets should be understood to be encompassed by this disclosure.

The discussion included in this application is intended to serve as abasic description. The reader should be aware that the specificdiscussion may not explicitly describe all embodiments possible; manyalternatives are implicit. It also may not fully explain the genericnature of the invention and may not explicitly show how each feature orelement can actually be representative of a broader function or of agreat variety of alternative or equivalent elements. Again, these areimplicitly included in this disclosure. Where the invention is describedin device-oriented terminology, each element of the device implicitlyperforms a function. Apparatus claims may not only be included for thedevices and circuits described, but also method or process claims may beincluded to address the functions the invention and each elementperforms. Neither the description nor the terminology is intended tolimit the scope of the claims that will be included in any subsequentpatent application.

It should also be understood that a variety of changes may be madewithout departing from the essence of the invention. Such changes arealso implicitly included in the description. They still fall within thescope of this invention. A broad disclosure encompassing both theexplicit embodiment(s) shown, the great variety of implicit alternativeembodiments, claims set forth in each priority case, claims supported byeach reference incorporated, and the broad methods or processes and thelike are encompassed by this disclosure and may be relied upon whendrafting claims for any subsequent patent application. It should beunderstood that such language changes and broader or more detailedclaiming may be accomplished at a later date. With this understanding,the reader should be aware that this disclosure is to be understood tosupport any subsequently filed patent application that may seekexamination of as broad a base of claims as deemed within theapplicant's right and may be designed to yield a patent coveringnumerous aspects of the invention both independently and as an overallsystem.

Further, each of the various elements of the invention and claims mayalso be achieved in a variety of manners. Additionally, when used orimplied, an element is to be understood as encompassing individual aswell as plural structures that may or may not be physically connected.This disclosure should be understood to encompass each such variation,be it a variation of an embodiment of any apparatus embodiment, a methodor process embodiment, or even merely a variation of any element ofthese. Particularly, it should be understood that as the disclosurerelates to elements of the invention, the words for each element may beexpressed by equivalent apparatus terms or method terms—even if only thefunction or result is the same. Such equivalent, broader, or even moregeneric terms should be considered to be encompassed in the descriptionof each element or action. Such terms can be substituted where desiredto make explicit the implicitly broad coverage to which this inventionis entitled. As but one example, it should be understood that allactions may be expressed as a means for taking that action or as anelement which causes that action. Similarly, each physical elementdisclosed should be understood to encompass a disclosure of the actionwhich that physical element facilitates. Regarding this last aspect, asbut one example, the disclosure of a “converter” should be understood toencompass disclosure of the act of “converting” or achieving a“conversion”—whether explicitly discussed or not—and, conversely, werethere effectively disclosure of the act of “converting” or a“conversion”, such a disclosure should be understood to encompassdisclosure of a “converter” and even a “means for converting” Suchchanges and alternative terms are to be understood to be explicitlyincluded in the description.

Any patents, publications, or other references mentioned in thisapplication for patent or its list of references are hereby incorporatedby reference in each of their entireties. Any priority case(s) claimedat any time by this or any subsequent application are hereby appendedand hereby incorporated by reference in their entirety. In addition, asto each term used it should be understood that unless its utilization inthis application is inconsistent with a broadly supportinginterpretation, common dictionary definitions should be understood asincorporated for each term and all definitions, alternative terms, andsynonyms such as contained in the Random House Webster's UnabridgedDictionary, second edition are hereby incorporated by reference.Finally, all references listed in the List of References otherinformation statement filed with or included in the application arehereby appended and hereby incorporated by reference, however, as toeach of the above, to the extent that such information or statementsincorporated by reference might be considered inconsistent with thepatenting of this/these invention(s) such statements are expressly notto be considered as made by the applicant(s).

Thus, the applicant(s) should be understood to have support to claim andmake a statement of invention to at least: i) each of the converters asherein disclosed and described, ii) the related methods disclosed anddescribed, iii) similar, equivalent, and even implicit variations ofeach of these devices and methods, iv) those alternative designs whichaccomplish each of the functions shown as are disclosed and described,v) those alternative designs and methods which accomplish each of thefunctions shown as are implicit to accomplish that which is disclosedand described, vi) each feature, component, and step shown as separateand independent inventions, vii) the applications enhanced by thevarious systems or components disclosed, viii) the resulting productsproduced by such systems or components, ix) each system, method, andelement shown or described as now applied to any specific field ordevices mentioned, x) methods and apparatuses substantially as describedhereinbefore and with reference to any of the accompanying examples, xi)the various combinations and permutations of each of the elementsdisclosed, xii) each potentially dependent claim or concept as adependency on each and every one of the independent claims or conceptspresented, and xiii) all inventions described herein. In addition and asto computerized aspects and each aspect amenable to programming or otherprogrammable electronic automation, the applicant(s) should beunderstood to have support to claim and make a statement of invention toat least: xiv) processes performed with the aid of or on a computer asdescribed throughout the above discussion, xv) a programmable apparatusas described throughout the above discussion, xvi) a computer readablememory encoded with data to direct a computer comprising means orelements which function as described throughout the above discussion,xvii) a computer configured as herein disclosed and described, xviii)individual or combined subroutines and programs as herein disclosed anddescribed, xix) the related methods disclosed and described, xx)similar, equivalent, and even implicit variations of each of thesesystems and methods, xxi) those alternative designs which accomplisheach of the functions shown as are disclosed and described, xxii) thosealternative designs and methods which accomplish each of the functionsshown as are implicit to accomplish that which is disclosed anddescribed, xxiii) each feature, component, and step shown as separateand independent inventions, and xxiv) the various combinations andpermutations of each of the above.

With regard to claims whether now or later presented for examination, itshould be understood that for practical reasons and so as to avoid greatexpansion of the examination burden or to meet prosecution rules, theapplicant may at any time present only initial claims or perhaps onlyinitial claims with only initial dependencies. The office and any thirdpersons interested in potential scope of this or subsequent applicationsshould understand that broader claims may be presented at a later datein this case, in a case claiming the benefit of this case, or in anycontinuation in spite of any preliminary amendments, other amendments,claim language, or arguments presented, thus throughout the pendency ofany case there is no intention to disclaim or surrender any potentialsubject matter. Both the examiner and any person otherwise interested inexisting or later potential coverage, or considering if there has at anytime been any possibility of an indication of disclaimer or surrender ofpotential coverage, should be aware that in the absence of explicitstatements, no such surrender or disclaimer is intended or should beconsidered as existing in this or any subsequent application.Limitations such as arose in Hakim v. Cannon Avent Group, PLC, 479 F.3d1313 (Fed. Cir 2007), or the like are expressly not intended in this orany subsequent related matter.

In addition, support should be understood to exist to the degreerequired under new matter laws—including but not limited to EuropeanPatent Convention Article 123(2) and United States Patent Law 35 USC 132or other such laws—to permit the addition of any of the variousdependencies or other elements presented under one independent claim orconcept as dependencies or elements under any other independent claim orconcept. In drafting any claims at any time whether in this applicationor in any subsequent application, it should also be understood that theapplicant has intended to capture as full and broad a scope of coverageas legally available. To the extent that insubstantial substitutes aremade, to the extent that the applicant did not in fact draft any claimso as to literally encompass any particular embodiment, and to theextent otherwise applicable, the applicant should not be understood tohave in any way intended to or actually relinquished such coverage asthe applicant simply may not have been able to anticipate alleventualities; one skilled in the art, should not be reasonably expectedto have drafted a claim that would have literally encompassed suchalternative embodiments.

Further, if or when used, the use of the transitional phrase“comprising” is used to maintain the “open-end” claims herein, accordingto traditional claim interpretation. Thus, unless the context requiresotherwise, it should be understood that the term “comprise” orvariations such as “comprises” or “comprising”, are intended to implythe inclusion of a stated element or step or group of elements or stepsbut not the exclusion of any other element or step or group of elementsor steps. Such terms should be interpreted in their most expansive formso as to afford the applicant the broadest coverage legally permissible.

Finally, any claims set forth at any time are hereby incorporated byreference as part of this description of the invention, and theapplicant expressly reserves the right to use all of or a portion ofsuch incorporated content of such claims as additional description tosupport any of or all of the claims or any element or component thereof,and the applicant further expressly reserves the right to move anyportion of or all of the incorporated content of such claims or anyelement or component thereof from the description into the claims orvice-versa as necessary to define the matter for which protection issought by this application or by any subsequent continuation, division,or continuation-in-part application thereof, or to obtain any benefitof, reduction in fees pursuant to, or to comply with the patent laws,rules, or regulations of any country or treaty, and such contentincorporated by reference shall survive during the entire pendency ofthis application including any subsequent continuation, division, orcontinuation-in-part application thereof or any reissue or extensionthereon.

1. A highly efficient method of series string solar energy powerconversion comprising the steps of: establishing a plurality of solarenergy sources, each providing a DC photovoltaic output; creating aplurality of high voltage highly varying DC photovoltaic outputs fromsaid plurality of solar energy sources; individually establishing eachof said high voltage, highly varying DC photovoltaic outputs as anindividual DC photovoltaic input to a plurality of individual highefficiency switchmode photovoltaic DC-DC converters; individually highefficiency conversion duty cycle controlling operation of a plurality ofswitch elements within each of said individual high efficiencyswitchmode photovoltaic DC-DC converters; photovoltaic boundarycondition controlling said plurality of switch elements within each ofsaid individual high efficiency switchmode photovoltaic DC-DCconverters; maximum photovoltaic power point controlling said pluralityof switch elements within each of said individual high efficiencyswitchmode photovoltaic DC-DC converters slaved to said step ofphotovoltaic boundary condition controlling said plurality of switchelements; feeding each of said high voltage, highly varying DCphotovoltaic outputs through a photovoltaic voltage increase modality ofphotovoltaic DC-DC power conversion; feeding each of said high voltage,highly varying DC photovoltaic outputs through a photovoltaic voltagedecrease modality of photovoltaic DC-DC power conversion responsive tosaid photovoltaic voltage increase modality of photovoltaic DC-DC powerconversion; slavedly individual panel dedicated maximum photovoltaicpower point DC-DC converting each of said high voltage, highly varyingDC photovoltaic outputs; boundary condition DC-DC converting said highvoltage, highly varying DC photovoltaic outputs; individuallysubstantially power isomorphically converting each said high voltage,highly varying DC photovoltaic outputs into a plurality of converted DCphotovoltaic outputs while accomplishing said step of individualdedicated maximum photovoltaic power point converting said DCphotovoltaic input from each of said plurality of solar panels; seriallyconnecting said plurality of converted DC photovoltaic outputs to createa combined higher voltage converted DC photovoltaic output from saidplurality of solar panels; establishing said combined higher voltageconverted DC photovoltaic output as a converted DC photovoltaic input toa high voltage, high power photovoltaic DC-AC inverter; and invertingsaid converted DC photovoltaic input into a high power inverted ACphotovoltaic output.
 2. A highly efficient method of series string solarenergy power conversion as described in claim 1 wherein said step ofindividually substantially power isomorphically converting each saidhigh voltage, highly varying DC photovoltaic outputs comprises the stepof capacitively storing parallel energy in a parallel capacitance.
 3. Ahighly efficient method of series string solar energy power conversionas described in claim 2 wherein said step of individually substantiallypower isomorphically converting each said high voltage, highly varyingDC photovoltaic outputs further comprises the step of high efficiencyswitching dual photovoltaic power interrupt switch elements.
 4. A highlyefficient method of series string solar energy power conversion asdescribed in claim 3 wherein said step of individually substantiallypower isomorphically converting each said high voltage, highly varyingDC photovoltaic outputs further comprises the step of high efficiencyswitching dual photovoltaic power shunt switch elements.
 5. A highlyefficient method of series string solar energy power conversion asdescribed in claim 4 wherein said step of individually substantiallypower isomorphically converting each said high voltage, highly varyingDC photovoltaic outputs further comprises the steps of: high efficiencyswitching a first photovoltaic power interrupt switch element having afirst input end and a first output end; high efficiency switching asecond photovoltaic power interrupt switch element having a second inputend connected to said first photovoltaic power interrupt switch elementconnected to said first photovoltaic power interrupt switch element,said second photovoltaic power interrupt switch element also having asecond output end; high efficiency switching a first photovoltaic powershunt switch element connected to said first photovoltaic powerinterrupt switch element at said first input end; high efficiencyswitching a second photovoltaic power shunt switch element connected tosaid second photovoltaic power interrupt switch element at said secondoutput end; and capacitively storing parallel energy in a parallelcapacitance connected at one end between said first photovoltaic powerinterrupt switch element and said second photovoltaic power interruptswitch element and connected across said first photovoltaic powerinterrupt switch element and said first photovoltaic power shunt switchelement and across said second photovoltaic power interrupt switchelement and said second photovoltaic power shunt switch element.
 6. Ahighly efficient method of series string solar energy power conversionas described in claim 5 wherein each said step of individuallysubstantially power isomorphically converting each said high voltage,highly varying DC photovoltaic outputs comprises a step selected from agroup consisting of the steps of: alternating between a first modalityof photovoltaic DC-DC power conversion and a second modality ofphotovoltaic DC-DC power conversion at least some times; photovoltaicload impedance increasing; photovoltaic load impedance decreasing; bothphotovoltaic load impedance increasing and photovoltaic load impedancedecreasing; photovoltaic voltage increasing; photovoltaic voltagedecreasing; both photovoltaic voltage increasing and then photovoltaicvoltage decreasing at least some times; controlling a photovoltaicconversion boundary condition; controlling a posterior photovoltaicoperating condition through control of a photovoltaic DC-DC converter;protecting a posterior photovoltaic element through control of aphotovoltaic DC-DC converter; disabling a photovoltaic conversion modethrough control of a photovoltaic DC-DC converter; protecting aphotovoltaic inverter through control of a photovoltaic DC-DC converter;controlling a photovoltaic DC-DC converter to coordinate withcharacteristics of a photovoltaic inverter; slavedly controlling aphotovoltaic conversion modality through a photovoltaic DC-DC converter;photovoltaic inverter slavedly controlling a photovoltaic conversionmodality through a photovoltaic DC-DC converter; maximum photovoltaicinverter current controlling a photovoltaic DC-DC converter;photovoltaic inverter operating condition controlling a photovoltaicDC-DC converter; photovoltaic converter operating condition controllinga photovoltaic DC-DC converter; slaved photovoltaic inverter operatingcondition controlling a photovoltaic DC-DC converter; slavedphotovoltaic load impedance increase controlling a photovoltaic DC-DCconverter; slaved photovoltaic load impedance decrease controlling aphotovoltaic DC-DC converter; slaved photovoltaic voltage increasecontrolling a photovoltaic DC-DC converter; slaved photovoltaic voltagedecrease controlling a photovoltaic DC-DC converter; both slavedphotovoltaic load impedance increase controlling a photovoltaic DC-DCconverter and slaved photovoltaic load impedance decrease controlling aphotovoltaic DC-DC converter; both slaved photovoltaic voltage increasecontrolling a photovoltaic DC-DC converter and slaved photovoltaicvoltage decrease controlling a photovoltaic DC-DC converter;photovoltaic boundary condition controlling a photovoltaic DC-DCconverter; posterior photovoltaic element protection controlling aphotovoltaic DC-DC converter; photovoltaic inverter protectioncontrolling a photovoltaic DC-DC converter; photovoltaic invertercoordinated controlling a photovoltaic DC-DC converter; and allpermutations and combinations of each of the above.
 7. A highlyefficient method of series string solar energy power conversion asdescribed in claim 6 wherein each said step of individually highefficiency conversion duty cycle controlling operation of a plurality ofswitch elements within each of said individual high efficiencyswitchmode photovoltaic DC-DC converters each comprises a step selectedfrom a group consisting of the steps of: threshold determinative dutycycle switching a photovoltaic DC-DC converter; switch frequencyalteration duty cycle switching a photovoltaic DC-DC converter; burstmode duty cycle switching a photovoltaic DC-DC converter; thresholddeterminative mode activation duty cycle switching a photovoltaic DC-DCconverter; threshold determinative mode deactivation duty cycleswitching a photovoltaic DC-DC converter; maximum voltage determinativeduty cycle switching a photovoltaic DC-DC converter; inverter maximumcurrent determinative duty cycle switching a photovoltaic DC-DCconverter; maximum photovoltaic power point duty cycle switching aphotovoltaic DC-DC converter; photovoltaic inverter maximum voltagedeterminative duty cycle switching a photovoltaic DC-DC converter;maximum photovoltaic voltage determinative duty cycle switching aphotovoltaic DC-DC converter; photovoltaic inverter maximum currentdeterminative duty cycle switching a photovoltaic DC-DC converter; allpermutations and combinations of each of the above.
 8. A highlyefficient method of series string solar energy power conversion asdescribed in claim 7 wherein said step of creating a plurality of highvoltage highly varying DC photovoltaic outputs from said plurality ofsolar energy sources comprises a step selected from a group consistingof the steps of: creating a plurality of high voltage highly varying DCphotovoltaic outputs having a voltage at least some times of at leastabout 15 volts; creating a plurality of high voltage highly varying DCphotovoltaic outputs having a voltage at least some times of at leastabout 57.1 volts; creating a plurality of high voltage highly varying DCphotovoltaic outputs having a voltage at least some times of at leastabout 84.2 volts; creating a plurality of high voltage highly varying DCphotovoltaic outputs having a voltage at least some times of at leastabout 100 volts; creating a plurality of high voltage highly varying DCphotovoltaic outputs having a voltage at least some times of at leastabout 105.3 volts; creating a plurality of high voltage highly varyingDC photovoltaic outputs having a voltage at least some times of at leastabout 114.2 volts; creating a plurality of high voltage highly varyingDC photovoltaic outputs having a voltage varying at least some timesover at least about 99.2 volts; creating a plurality of high voltagehighly varying DC photovoltaic outputs having a voltage varying at leastsome times over at least about 57.1 volts; creating a plurality of highvoltage highly varying DC photovoltaic outputs having a voltage varyingat least some times over at least about 21.1 volts; creating a pluralityof high voltage highly varying DC photovoltaic outputs having a voltagevarying at least some times over a range of at least about 1.25:1;creating a plurality of high voltage highly varying DC photovoltaicoutputs having a voltage varying at least some times over a range of atleast about 2:1; creating a plurality of high voltage highly varying DCphotovoltaic outputs having a voltage varying at least some times over arange of at least about 7.6:1; creating a plurality of high voltagehighly varying DC photovoltaic outputs having a voltage varying at leastsome times from at least about 57.1 volts to at least about 114.2 volts;creating a plurality of high voltage highly varying DC photovoltaicoutputs having a voltage varying at least some times from at least about84.2 volts to at least about 105.3 volts; and creating a plurality ofhigh voltage highly varying DC photovoltaic outputs having a voltagevarying at least some times from at least about 15 volts to at leastabout 114.2 volts.
 9. A highly efficient method of series string solarenergy power conversion as described in claim 8 wherein said step ofserially connecting said plurality of converted DC photovoltaic outputsto create a combined higher voltage converted DC photovoltaic outputfrom said plurality of solar panels comprises a step selected from agroup consisting of the steps of: creating a combined higher voltageconverted DC photovoltaic output having a voltage at least some times ofat least about 400 volts; creating a combined higher voltage convertedDC photovoltaic output having a voltage at least some times of at leastabout 1000 volts; creating a combined higher voltage converted DCphotovoltaic output having a voltage at least some times of at leastabout hundreds of volts; creating a combined higher voltage converted DCphotovoltaic output having a power at least some times of at least about300 watts; creating a combined higher voltage converted DC photovoltaicoutput having a power at least some times of at least about 350 watts;creating a combined higher voltage converted DC photovoltaic outputhaving a power at least some times of at least about 380 watts; creatinga combined higher voltage converted DC photovoltaic output having apower at least some times of at least about a megawatt; and creating acombined higher voltage converted DC photovoltaic output having a powerat least some times of at least megawatts.
 10. A highly efficient methodof series string solar energy power conversion as described in claim 9wherein each said step of individually substantially powerisomorphically converting each said high voltage, highly varying DCphotovoltaic outputs comprises a step selected from a group consistingof: solar power converting with at least about 97% efficiency, solarpower converting with at least about 97.5% efficiency, solar powerconverting with at least about 98% efficiency, solar power convertingwith at least about 98.5% efficiency, solar power converting with atleast about 97% up to about 99.2% efficiency, solar power convertingwith at least about 97.5% up to about 99.2% efficiency, solar powerconverting with at least about 98% up to about 99.2% efficiency, solarpower converting with at least about 98.5% up to about 99.2% efficiency,solar power converting with at least about 97% up to about wiretransmission loss efficiency, solar power converting with at least about97.5% up to about wire transmission loss efficiency, solar powerconverting with at least about 98% up to about wire transmission lossefficiency, and solar power converting with at least about 98.5% up toabout wire transmission loss efficiency.
 11. A highly efficient methodof series string solar energy power conversion as described in claim 5wherein each said step of individually high efficiency conversion dutycycle controlling operation of a plurality of switch elements withineach of said individual high efficiency switchmode photovoltaic DC-DCconverters each comprises the step of burst mode duty cycle switching aphotovoltaic DC-DC converter.
 12. A highly efficient method of seriesstring solar energy power conversion comprising the steps of:establishing a plurality of solar energy sources, each providing a DCphotovoltaic output; creating a plurality of high voltage highly varyingDC photovoltaic outputs from said plurality of solar energy sources;individually establishing each of said high voltage, highly varying DCphotovoltaic outputs as an individual DC photovoltaic input to aplurality of individual high efficiency switchmode photovoltaic DC-DCconverters; individually high efficiency conversion duty cyclecontrolling operation of a plurality of switch elements within each ofsaid individual high efficiency switchmode photovoltaic DC-DCconverters; maximum photovoltaic power point controlling said pluralityof switch elements within each of said individual high efficiencyswitchmode photovoltaic DC-DC converters; feeding each of said highvoltage, highly varying DC photovoltaic outputs through a photovoltaicvoltage increase modality of photovoltaic DC-DC power conversion;feeding each of said high voltage, highly varying DC photovoltaicoutputs through a photovoltaic voltage decrease modality of photovoltaicDC-DC power conversion responsive to said photovoltaic voltage increasemodality of photovoltaic DC-DC power conversion; individual paneldedicated maximum photovoltaic power point DC-DC converting each of saidhigh voltage, highly varying DC photovoltaic outputs; individuallysubstantially power isomorphically converting each said high voltage,highly varying DC photovoltaic outputs into a plurality of converted DCphotovoltaic outputs while accomplishing said step of individualdedicated maximum photovoltaic power point converting said DCphotovoltaic input from each of said plurality of solar panels; seriallyconnecting said plurality of converted DC photovoltaic outputs to createa combined higher voltage converted DC photovoltaic output from saidplurality of solar panels; establishing said combined higher voltageconverted DC photovoltaic output as a converted DC photovoltaic input toa traditional high voltage, high power photovoltaic DC-AC inverter; andtraditionally inverting said converted DC photovoltaic input into a highpower inverted AC photovoltaic output.
 13. A highly efficient method ofseries string solar energy power conversion as described in claim 12wherein said step of individually substantially power isomorphicallyconverting each said high voltage, highly varying DC photovoltaicoutputs comprises the step of capacitively storing parallel energy in aparallel capacitance.
 14. A highly efficient method of series stringsolar energy power conversion as described in claim 13 wherein said stepof individually substantially power isomorphically converting each saidhigh voltage, highly varying DC photovoltaic outputs further comprisesthe step of high efficiency switching dual photovoltaic power interruptswitch elements.
 15. A highly efficient method of series string solarenergy power conversion as described in claim 14 wherein said step ofindividually substantially power isomorphically converting each saidhigh voltage, highly varying DC photovoltaic outputs further comprisesthe step of high efficiency switching dual photovoltaic power shuntswitch elements.
 16. A highly efficient method of series string solarenergy power conversion as described in claim 15 wherein said step ofindividually substantially power isomorphically converting each saidhigh voltage, highly varying DC photovoltaic outputs further comprisesthe steps of: high efficiency switching a first photovoltaic powerinterrupt switch element having a first input end and a first outputend; high efficiency switching a second photovoltaic power interruptswitch element having a second input end connected to said firstphotovoltaic power interrupt switch element connected to said firstphotovoltaic power interrupt switch element, said second photovoltaicpower interrupt switch element also having a second output end; highefficiency switching a first photovoltaic power shunt switch elementconnected to said first photovoltaic power interrupt switch element atsaid first input end; high efficiency switching a second photovoltaicpower shunt switch element connected to said second photovoltaic powerinterrupt switch element at said second output end; and capacitivelystoring parallel energy in a parallel capacitance connected at one endbetween said first photovoltaic power interrupt switch element and saidsecond photovoltaic power interrupt switch element and connected acrosssaid first photovoltaic power interrupt switch element and said firstphotovoltaic power shunt switch element and across said secondphotovoltaic power interrupt switch element and said second photovoltaicpower shunt switch element.
 17. A highly efficient method of seriesstring solar energy power conversion as described in claim 16 whereineach said step of individually substantially power isomorphicallyconverting each said high voltage, highly varying DC photovoltaicoutputs comprises a step selected from a group consisting of the stepsof: alternating between a first modality of photovoltaic DC-DC powerconversion and a second modality of photovoltaic DC-DC power conversionat least some times; photovoltaic load impedance increasing;photovoltaic load impedance decreasing; both photovoltaic load impedanceincreasing and photovoltaic load impedance decreasing; photovoltaicvoltage increasing; photovoltaic voltage decreasing; both photovoltaicvoltage increasing and then photovoltaic voltage decreasing at leastsome times; controlling a photovoltaic conversion boundary condition;controlling a posterior photovoltaic operating condition through controlof a photovoltaic DC-DC converter; protecting a posterior photovoltaicelement through control of a photovoltaic DC-DC converter; disabling aphotovoltaic conversion mode through control of a photovoltaic DC-DCconverter; protecting a photovoltaic inverter through control of aphotovoltaic DC-DC converter; controlling a photovoltaic DC-DC converterto coordinate with characteristics of a photovoltaic inverter; slavedlycontrolling a photovoltaic conversion modality through a photovoltaicDC-DC converter; photovoltaic inverter slavedly controlling aphotovoltaic conversion modality through a photovoltaic DC-DC converter;maximum photovoltaic inverter current controlling a photovoltaic DC-DCconverter; photovoltaic inverter operating condition controlling aphotovoltaic DC-DC converter; photovoltaic converter operating conditioncontrolling a photovoltaic DC-DC converter; slaved photovoltaic inverteroperating condition controlling a photovoltaic DC-DC converter; slavedphotovoltaic load impedance increase controlling a photovoltaic DC-DCconverter; slaved photovoltaic load impedance decrease controlling aphotovoltaic DC-DC converter; slaved photovoltaic voltage increasecontrolling a photovoltaic DC-DC converter; slaved photovoltaic voltagedecrease controlling a photovoltaic DC-DC converter; both slavedphotovoltaic load impedance increase controlling a photovoltaic DC-DCconverter and slaved photovoltaic load impedance decrease controlling aphotovoltaic DC-DC converter; both slaved photovoltaic voltage increasecontrolling a photovoltaic DC-DC converter and slaved photovoltaicvoltage decrease controlling a photovoltaic DC-DC converter;photovoltaic boundary condition controlling a photovoltaic DC-DCconverter; posterior photovoltaic element protection controlling aphotovoltaic DC-DC converter; photovoltaic inverter protectioncontrolling a photovoltaic DC-DC converter; photovoltaic invertercoordinated controlling a photovoltaic DC-DC converter; and allpermutations and combinations of each of the above.
 18. A highlyefficient method of series string solar energy power conversion asdescribed in claim 17 wherein each said step of individually highefficiency conversion duty cycle controlling operation of a plurality ofswitch elements within each of said individual high efficiencyswitchmode photovoltaic DC-DC converters each comprises a step selectedfrom a group consisting of the steps of: threshold determinative dutycycle switching a photovoltaic DC-DC converter; switch frequencyalteration duty cycle switching a photovoltaic DC-DC converter; burstmode duty cycle switching a photovoltaic DC-DC converter; thresholddeterminative mode activation duty cycle switching a photovoltaic DC-DCconverter; threshold determinative mode deactivation duty cycleswitching a photovoltaic DC-DC converter; maximum voltage determinativeduty cycle switching a photovoltaic DC-DC converter; inverter maximumcurrent determinative duty cycle switching a photovoltaic DC-DCconverter; maximum photovoltaic power point duty cycle switching aphotovoltaic DC-DC converter; photovoltaic inverter maximum voltagedeterminative duty cycle switching a photovoltaic DC-DC converter;maximum photovoltaic voltage determinative duty cycle switching aphotovoltaic DC-DC converter; photovoltaic inverter maximum currentdeterminative duty cycle switching a photovoltaic DC-DC converter; allpermutations and combinations of each of the above.
 19. A highlyefficient method of series string solar energy power conversion asdescribed in claim 18 wherein each said step of individuallysubstantially power isomorphically converting each said high voltage,highly varying DC photovoltaic outputs comprises a step selected from agroup consisting of: solar power converting with at least about 97%efficiency, solar power converting with at least about 97.5% efficiency,solar power converting with at least about 98% efficiency, solar powerconverting with at least about 98.5% efficiency, solar power convertingwith at least about 97% up to about 99.2% efficiency, solar powerconverting with at least about 97.5% up to about 99.2% efficiency, solarpower converting with at least about 98% up to about 99.2% efficiency,solar power converting with at least about 98.5% up to about 99.2%efficiency, solar power converting with at least about 97% up to aboutwire transmission loss efficiency, solar power converting with at leastabout 97.5% up to about wire transmission loss efficiency, solar powerconverting with at least about 98% up to about wire transmission lossefficiency, and solar power converting with at least about 98.5% up toabout wire transmission loss efficiency.
 20. A highly efficient methodof series string solar energy power conversion as described in claim 16wherein each said step of individually high efficiency conversion dutycycle controlling operation of a plurality of switch elements withineach of said individual high efficiency switchmode photovoltaic DC-DCconverters each comprises the step of burst mode duty cycle switching aphotovoltaic DC-DC converter.